When you know both yourself as well as your competition, you are never in danger. To know yourself and not others, gives you half a chance of winning. Knowing neither yourself or your competition puts you in a position to lose.
A vow is fixed and unalterable determination to do a thing, when such a determination is related to something noble which can only uplift the man who makes the resolve.
The most important thing in life is to stop saying 'I wish' and start saying 'I will.' Consider nothing impossible, then treat possibilities as probabilities.